running rough

[84cucv1ton]

trying to help this kid out. got a m1008 from a town auction for 480. this thing had a hard life it looks.. got it running.. on the pass side by the firewall there is a bolt where the senser should be.. i cant think of what that senser does right now.. could that be why its running rough?? bleed the fuel filter all 8 lines. helped a bit but not much..

ideas?? thanks again

 

[Matt65]

Do you have a picture available of the missing sensor? The only thing that comes to mind in that area would be the Fuel filter Water sensor.?., But thats a total stab in the dark.

There is a section in the TMs for trouble shooting rough running etc. It may be that the sensor you see missing is not related to the main symptom of rough running.

 

[aggopian]

Also it would help to know if it's rough at idle or off idle?
Is there excessive smoke?
If so what color?

 

[iluvbudwsr]

I'm also taking stab in the dark. My truck also came without the water sensor. A lot of people just take them off and if you don't seal that hole up properly it will certainly make your truck run rough, especially during start-ups. Does the "water in fuel" light stay on or does it go off after start up?
If this is the case, you need to take that screw out and fill that hole with some JB Weld because no air can leak though that hole. It has to be sealed tight...

 

[84cucv1ton]

so you guys have a better understanding. its in the block on the pass side right up by the firewall... here is a pic of what should be there:
http://www.amazon.com/ACDelco-10154...SW/ref=sr_1_49?ie=UTF8&qid=1331917221&sr=8-49

thanks again

 

[CUCVFAN]

In the back of the passenger side is the cold advance sensor. And, that is what it looks like. It applies power to the green wire on the pump if the engine is cold. It is normally closed, so without it, it will not idle up or advance the pump normally when cold. I doubt that is causing the rough running, unless it is only when cold at idle. Even then, it's probably not critical.

Clogged injectors? As aggopian asked: What are the symptoms?

 

[combatmech]

Do you know the last time the fuel filter had been changed? Mine was running like poo-poo a while back, changed the fuel filter and she runs like an almost new truck. My old filter had an 07 date written on it.
Ditto The item you have linked is the cold idle sensor. That sensor is mounted on the back, right side of the engine.

 

[84cucv1ton]

fuel filter is new. bleed filter and lines 3 times.. very little to no smoke... a bit only at start up.. cold and wrmed up its running rough. the whole truck shakes a bit.. i ordered the cold advance sensor. have a new one in a few days.. he ran a full bottle of fuel treatment in the first fuel tank.. thanks again

 

[emmado22]

Perhaps it is old/bad fuel?

 

[jdeoliveira74]

maybe someone messed with ip pump timing?? could also be bad motor mounts if they are shot could give the apperance of a rough running engine and will vibrate like crazy

 

[84cucv1ton]

never thought of motor mounts.. truck has 90% new fuel in it. will take a look

 

[84cucv1ton]

motor mounts look find. Tank is filled all way of new fuel. Added a bottle of locus fuel treatment. Whole bottle. Hopefully get that sensor in the mail today. bleed the fuel lines 2 more times. Little bit smoother. Fuel is definitely getting to the injectors. Still pretty rough though. Thought we would have this truck going by now. This is a hard one. Pretty frustrating. Working on it though

 

[allenhillview]

Fuel return valve on IP , right where return goes in by the cold advance on IP.

Take out and clean, there is plenty of threads on this fix or buy new one, some break glass ball out, some say if its clogged IP pump is on it's last leg, give it try at least you will know, 10 minute job and another thing checked.

 

[84cucv1ton]

ok thanks.. didnt think of that one

 

[ryan77]

Ive got the same problem with my m1009 i just got! Idles very rough smooths out when u rev it up! Im pulling my hair out like you are. Im trying a electric fuel pump as my next step.

 

[lindyp38]

id run a few tankfuls of fuel through it....especially if has been sitting awhile......its that 10percent in the tank that will make life difficult......

if u havent already done so...do ur normal maintenance.......good luck....post some pics of ur truck ......id like to see it....

 

[84cucv1ton]

been working on this for a while now. Very easy driving no towing or anything. 2 complete fuel tanks ran down. on the third tank now all three tanks with a heavy dose of fuel treatment. Still run rough. I'll get some pictures. This kid might buy something else now. For some reason. This truck might become mine.
Also looked around for cracked hoses. To see if somewhere was sucked in air. Didn't see anything. Feel like i hit a wall there something I am missingI

 

[Barrman]

If the return valve on the pump is clean. Then the pump probably isn't shedding its parts. That does not mean the pump is good.

My 1009 idles like it was only firing on 7 cylinders. I loosened each injector line at the injector with the engine running. All had fuel and all caused the idle to slow down. I was getting 20-22 mpg highway and the thing started every time.

I put a new pump on it, it idles smooth and steady and all is well. This is a 25 year old vehicle with who know how many years and miles on the parts that wear. Check the fuel system for leaks and change the filters. Then, do some basic troubleshooting. After that, it might just be time for a new IP.

 

[ryan77]

Mine runs like that! Im doing a new pump and injectors!

 

[84cucv1ton]

true barrman.. I have a injection pump. Getting injectors together tomorrow to send out to be rebuilt. Looks like it's going to be my truck. Thanks for the help